Contemporary cable systems bring data, voice, and video to subscribers by coaxial cable to end points such as telephones, modems for computers, and set-top boxes for televisions. The coaxial cable runs from an outside plant, for example, a pole or underground feed, to an outside box or terminal, at the destination building, such as a business, residence, or multi-unit dwelling. In the outside box, splitters divide the cable for the interior system or interior wiring, where individual coaxial cables link and provide signals to telephones, set-top boxes, and modems. Since electrical signals are transmitted over the external and interior coaxial cables, the National Electrical Code requires the shields of coaxial cables to be grounded. This grounding typically occurs on an exterior coaxial cable, such as the coaxial cable that runs from the outside plant to the outside box or terminal.
For example, as shown in FIG. 1, for multi-unit buildings such as an apartment building 100 with three apartments 100a, 100b, 100c, and a basement 100d, each apartment 100a-100c is shown receiving cable service. This service, for example, includes voice, data, and video that are delivered from an outside plant 102 to a terminal 104 over an exterior coaxial cable 106. The exterior coaxial cable 106 is in two sections 106a, 106b. At the terminal 104, splitter (SP) 108 divides the exterior coaxial cable 106, for example, into two Category 5 lines 110, 112 for voice and data, respectively, and coaxial cable 114 for video for each apartment. Line 110 carries voice for telephones 120. Line 112 carries data for computer modems 122 of computers 122a, and coaxial cable 114 carries video signals for set top boxes 124 of televisions 124a. 
The exterior coaxial cable 106 is grounded, for example, by a conventional supplemental adapter 126, as shown in detail in FIG. 1B. The supplemental adapter 126 receives the coaxial cable sections 106a, 106b, and grounds the coaxial cable 106 via a ground wire 128, as shown in FIG. 1. The ground wire 128 connects to a ground source, such as the ground or a grounded structure, such as a water pipe (not shown). By grounding the exterior coaxial cable 106, the coaxial cable 114, by its being electrically connected to the coaxial cable 106, is also grounded.
The supplemental ground adapter 126 includes a frame 130 with a cylindrical portion 132 for supporting threaded barrels 134a, 134b. The sections 106a, 106b of the exterior coaxial cable attach to the respective barrels 134a, 134b. Frame 130 includes flanges 136a, 136b with openings 138a, 138b for screws that attach to a support structure, such as a wall of the building 100 or the like. A body portion 140 includes a bore 142 for receiving the ground wire 128 (FIG. 1) and a tapped hole (not shown) for receiving a screw 144. The screw 144 clamps the ground wire 128 in a secure physical contact with the body portion 140, resulting in a secure electrical contact therewith.
Since the demand for broadband bandwidth has increased to accommodate advanced generations of voice, video, and data transmission, fiber optic cable is rapidly replacing coaxial cable. FIG. 2 shows the delivery method and system for voice, video, and data known as “fiber to the home.” For multi-unit buildings such as an apartment building 200 with three apartments 200a, 200b, 200c, and a basement 200d, each apartment 200a-200c is shown receiving broadband service. This service, for example, includes voice, data, and video, which is delivered from an outside plant 202 to a terminal or communications room 204 of the building 200 over fiber optic lines 206.
Splitter (SP) 208 divides the fiber optic lines 202 into three fiber optic lines 210, each connected to an interior optical network terminal (ONT) 212 residing in a different apartment 200a, 200b, 200c. Each interior ONT 212 converts optical signals, received from a corresponding fiber optic line 210, into electrical signals for transmission to (i) voice devices, such as telephone 220, (ii) data devices, such as modems 222 for computers 222a, and (iii) video devices, such as set top-boxes 224 for televisions 224a, and vice versa for converting electrical signals from those devices into optical signals for transmission over fiber optic line 202. Voice devices 220 connect to the interior ONT 212 by regular telephone wiring 230 into conventional telephone ports of the ONT 212, and data devices 222 connect to the interior ONT 212 by Category 5 cable 232 into conventional ports. However, set-top boxes 224 connect to the interior ONT 212 by a coaxial cable 234. Since coaxial cable 234 is located entirely within building 208, it is referred to as an interior coaxial cable or interior wiring.
The replacement of the external coaxial cables and some interior coaxial cables with fiber optic cables has made obsolete the traditional approach to providing grounding for the interior coaxial cable. Unlike coaxial cable, fiber optic cable does not carry electrical signals and, accordingly, is non-conducting. The National Electrical Code does not specify grounding for non-conducting fiber runs into buildings and, also, does not specify grounding for interior coaxial cables and other interior wiring fed by non-conducting fiber optic cables. However, many government authorities and customers insist on grounding of these interior coaxial cables.
There are two prevailing solutions for grounding interior coaxial cables, like coaxial cables 234. A first solution involves coupling a supplemental ground adapter, such as the adapter 126 of FIG. 1B or a similar structure, to the coaxial cable and running a ground wire from the adapter to ground. This method exhibits drawbacks as it adds two connections, each connection causing signal loss, as well as an additional piece of hardware that must be stocked by installers.
FIG. 3 shows another solution, where a ground wire 302 is directly connected by a conductive metal rivet 304 to the conductive metal traces 306 or ground of the printed circuit board (PCB) 308 of the ONT 310. In this solution, the ground path runs through the PCB 308, which places the PCB 308 at the risk of failing. Additionally, the ground path may transfer the ground fault directly through other circuits on the PCB 308, resulting in the ONT 310 being destroyed.